1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // constexpr lazy_split_view(View base, Pattern pattern);
13 
14 #include <ranges>
15 
16 #include <cassert>
17 #include <string_view>
18 #include <utility>
19 #include "types.h"
20 
21 struct ViewWithCounting : std::ranges::view_base {
22   int* times_copied = nullptr;
23   int* times_moved = nullptr;
24 
25   constexpr ViewWithCounting(int& copies_ctr, int& moves_ctr) : times_copied(&copies_ctr), times_moved(&moves_ctr) {}
26 
27   constexpr ViewWithCounting(const ViewWithCounting& rhs)
28     : times_copied(rhs.times_copied)
29     , times_moved(rhs.times_moved) {
30     ++(*times_copied);
31   }
32   constexpr ViewWithCounting(ViewWithCounting&& rhs)
33     : times_copied(rhs.times_copied)
34     , times_moved(rhs.times_moved) {
35     ++(*times_moved);
36   }
37 
38   constexpr const char* begin() const { return nullptr; }
39   constexpr const char* end() const { return nullptr; }
40 
41   constexpr ViewWithCounting& operator=(const ViewWithCounting&) = default;
42   constexpr ViewWithCounting& operator=(ViewWithCounting&&) = default;
43   constexpr bool operator==(const ViewWithCounting&) const { return true; }
44 };
45 static_assert(std::ranges::forward_range<ViewWithCounting>);
46 static_assert(std::ranges::view<ViewWithCounting>);
47 
48 constexpr bool test() {
49   // Calling the constructor with `(ForwardView, ForwardView)`.
50   {
51     CopyableView input = "abc def";
52     std::ranges::lazy_split_view<CopyableView, CopyableView> v(input, " ");
53     assert(v.base() == input);
54   }
55 
56   // Calling the constructor with `(InputView, TinyView)`.
57   {
58     InputView input = "abc def";
59     std::ranges::lazy_split_view<InputView, ForwardTinyView> v(input, ' ');
60     // Note: `InputView` isn't equality comparable.
61     (void)v;
62   }
63 
64   // Make sure the arguments are moved, not copied.
65   {
66     using View = ViewWithCounting;
67     using Pattern = ViewWithCounting;
68 
69     // Arguments are lvalues.
70     {
71       int view_copied = 0, view_moved = 0, pattern_copied = 0, pattern_moved = 0;
72       View view(view_copied, view_moved);
73       Pattern pattern(pattern_copied, pattern_moved);
74 
75       std::ranges::lazy_split_view<View, Pattern> v(view, pattern);
76       assert(view_copied == 1); // The local variable is copied into the argument.
77       assert(view_moved == 1);
78       assert(pattern_copied == 1);
79       assert(pattern_moved == 1);
80     }
81 
82     // Arguments are rvalues.
83     {
84       int view_copied = 0, view_moved = 0, pattern_copied = 0, pattern_moved = 0;
85       std::ranges::lazy_split_view<View, Pattern> v(
86           View(view_copied, view_moved), Pattern(pattern_copied, pattern_moved));
87       assert(view_copied == 0);
88       assert(view_moved == 1);
89       assert(pattern_copied == 0);
90       assert(pattern_moved == 1);
91     }
92   }
93 
94   return true;
95 }
96 
97 int main(int, char**) {
98   test();
99   static_assert(test());
100 
101   return 0;
102 }
103